On Tue, Dec 05, 2017 at 04:40:27PM -0500, Harish Kasiviswanathan wrote:
> create = dio->op == REQ_OP_WRITE;
> - if (dio->flags & DIO_SKIP_HOLES) {
> + if (dio->flags & DIO_SKIP_HOLES &&
> + i_size_read(dio->inode) > 0) {
> if (fs_startblk <= ((i_size_read(dio->inode) - 1) >>
> i_blkbits))
i_size_read() isn't cheap on 32-bit SMP ... do we actually need to sample
it at all here, or is it enough to use the i_size that was sampled earlier?
IOW:
create = dio->op == REQ_OP_WRITE;
- if (dio->flags & DIO_SKIP_HOLES) {
- if (fs_startblk <= ((i_size_read(dio->inode) - 1) >>
- i_blkbits))
+ if (dio->flags & DIO_SKIP_HOLES && dio->i_size) {
+ if (fs_startblk <= (dio->i_size - 1) >> i_blkbits))
Another possibility would be to tweak the comparison slightly ...
if (dio->flags & DIO_SKIP_HOLES) {
- if (fs_startblk <= ((i_size_read(dio->inode) - 1) >>
- i_blkbits))
+ if (fs_startblk < ((i_size_read(dio->inode) +
+ (1UL << i_blkbits) - 1) >> i_blkbits))
Or we could use a temporary variable to avoid reading i_size twice.
